When an elongated member used for medical care, such as a catheter or a guide wire, is to be introduced into a living organism, an introducer (medical tool) is used. An example of one such introducer is disclosed in Japanese Patent Publication No. Hei 2-949.
This introducer is composed of a hub having a tubular shape, a sheath having a cap mounted at one end portion of the hub and a sheath tube connected to the other end portion of the hub, and a dilator which is inserted into and used together with the sheath in order to facilitate introduction of the sheath into a living organism. An opening is provided in the cap such that it is communicated with a hollow portion of the hub. A valve body having a disk shape covers the opening to maintain a liquid-tight state of the hollow portion of the hub.
The valve body is made of an elastic material such as silicone rubber and has two slits formed thereon that intersect crosswise with each other. The slits are placed into an open state when an elongated member (pipe body) is inserted into the sheath, but are placed into a closed state when the elongated member is pulled off from the sheath.
However, with such a valve body as just described, if an elongated member is kept inserted for a long period of time or insertion and pulling off of an elongated member are repeated frequently, a tear may occur with the slits, and there is the possibility that the tear may further advance.
If a tear occurs with the slits, when the elongated medical member is pulled off and the slits are closed, the liquid-tightness of the valve body (slits) may be deteriorated (damaged) by the tear. This may also be the case even when the elongated member is positioned in the valve body.
Further, even if a tear does not occur, for example, when coagulations or the like of the blood stick in the sheath are sucked and removed through the side port, since the inside of the sheath is placed into a negative pressure state, there is the possibility that a central portion of the valve body may be drawn into the inside of the sheath to open the slits thereby to allow air to be sucked into the inside of the sheath from the outside.
In this manner, the prior art valve body described above is not fully satisfactory with respect to sealability (sealing performance).